The opinions expressed in this commentary are solely those of Paul R. La Monica. Other than Time Warner, the parent of CNNMoney, and Abbott Laboratories, La Monica does not own positions in any individual stocks.

Investors were giddy Thursday after European Central Bank president Mario Draghi appeared to borrow Hank Paulson's old bazooka. Stocks surged after Draghi said that the ECB would do anything and everything it could to save the euro -- the strongest language yet by anyone in a position to help end the continent's debt crisis. A bigger-than-expected drop in jobless claims in the U.S. was also lifting traders' spirits.

So of course, it's time to rain on everybody's parade a bit.

If you look at how the markets have behaved since the dawn of the financial crisis in 2008, stocks often get tripped up by so-called Black Swan events -- named for the Nassim Nicholas Taleb book and not the creepy Natalie Portman ballerina movie. A financial Black Swan is a true surprise that is either hard to predict or has been flying under the radar thanks to the collective blissful ignorance of investors.

Last year's Japanese earthquake/tsunami is an example of a Black Swan that truly can't be predicted -- even by seismologists. But the disaster had a tangible impact on the global economy and markets. One could also argue that the beginning stages of the Europe debt crisis in 2010 (when Greece morphed from birthplace of democracy to birthplace of European financial chaos) was also a Black Swan. People should have seen it coming but didn't.

One market strategist I recently spoke to told me he's worried that Iran is the biggest risk that nobody is focusing on right now. That makes it a prime candidate to be the next Black Swan. Everyone already knows that Europe remains a mess, the U.S. is approaching the fiscal cliff of tax hikes and big automatic budget cuts, and that China's economy is cooling. It's not that hard to position a portfolio for that.

But what if say, an increasingly agitated Iran -- which is starting to feel the strain of recent economic sanctions -- decides to do some more saber rattling?

Marty Leclerc, founder of Barrack Yard Advisors, an investment firm in Bryn Mawr, Pa., said he's concerned that Iran could wreak havoc on the commodities and stock markets if it decided to step up militarily against Israel or others in the region as a means of distracting Iranian citizens from the troubles in its economy.

"There are lots of risks in the short-term for the market. But the unknown known, if you will, is Iran," Leclerc said. "The sanctions are working and that is having a negative effect on Iran's economy. The Mullahs may have to respond."

Leclerc said that more problems in Europe, the U.S. and China are arguably priced into the markets. A huge, sudden spike in the price of oil following a geopolitical conflict is not. The recent pullback in oil and gas prices has been a welcome respite for consumers. A skirmish or two that pushed crude prices back above $100 a barrel and a gallon of gas back toward $4 could have a disastrous effect on what's still a very fragile recovery in the U.S.

Of course, Iran may stay quiet. But last I checked, the Middle East is an insanely volatile region. It would not be a huge surprise if another crisis developed there ... and it would be foolish to ignore the possible impact it could have on the economy and markets.